supply power from Nucleo STM32G4

[Jad]

Good morning.

I am wiling to use the STM32G4 Nucleo-32 board (MB1430) board for an analog to CAN use.

 

I would like to know if I could power up my 10 5V sensors. so i would like to know if I can use the +5V of my board and the current capacity of it to power up my sensors.

 

My other question would be around the power supply of the board, It seems logical to use 7V and 800 mA to power it up so I will have as much power possible to use my 5V for my sensors. Is it the correct way to think?

 

I would also like to know if i Have a 14 Volt battery, if I can directly put 2 boards in serial, the regulator inside of them making always sure that the tension is stable even if there is current variation in the circuit.

[SofLit]

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@Jad wrote:

Good morning.

I am wiling to use the STM32G4 Nucleo-32 board (MB1430) board for an analog to CAN use.

 

I would like to know if I could power up my 10 5V sensors. so i would like to know if I can use the +5V of my board and the current capacity of it to power up my sensors.

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That depends on the load that LD1117 (the 5V regulator) will reach with your sensors. According to its datasheet the current should not exceed 800 mA of output current:

The load includes the supply of the MCU + LDO regulator LD39050P (5V to 3.3V).

[Andrew Neil]

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@Jad wrote:

I would like to know if I could power up my 10 5V sensors. so i would like to know if I can use the +5V of my board and the current capacity of it to power up my sensors.

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Yes - so long as the total of the Nucleo board and all your sensors doesn't exceed the power supply capacity.

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@Jad wrote:

My other question would be around the power supply of the board, It seems logical to use 7V and 800 mA to power it up so I will have as much power possible to use my 5V for my sensors.

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The limiting factor here is going to be the power dissipation in the regulator - see Table 5 in the User Manual:

https://www.st.com/resource/en/user_manual/um2397-stm32g4-nucleo32-board-mb1430-stmicroelectronics.pdf#page=13

So, from a 7V input, it should be able to give 800mA total for both the Nucleo itself and any added loads.

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@Jad wrote:

I would also like to know if i Have a 14 Volt battery, if I can directly put 2 boards in serial

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I think not.

[Jad]

thank you for the response, I saw the table of the current depending of the voltage, it is to maximise the power that i chose the 7 V input so I could get an output of 800 mA. I would like to know how to calculate how much supply my MCU would need, then to know the power that I can still use I do P(source) - (Pmcu) right?. If I do not use the 3.3V output i can not take care of the LDO regulator LD39050P (5V to 3.3V) right? 

[SofLit · Accepted solution]

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@Jad wrote:

I would like to know how to calculate how much supply my MCU would need

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Measure the consumption on JP1 while running the application:

But seems not only the target MCU that pulls the current from LD1117 but also the STLINK block: MCU+LDO+ LEDs:

[Andrew Neil]

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@Jad wrote:

 I would like to know how to calculate how much supply my MCU would need,

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As @SofLit said, the easiest way is to measure it.

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@Jad wrote:

then to know the power that I can still use I do P(source) - (Pmcu) right?

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Yes.

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@Jad wrote:

 If I do not use the 3.3V output i can not take care of the LDO regulator LD39050P (5V to 3.3V) right? 

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I'm not sure what you mean by that.

Figure 8 in the UM shows you how all the various supplies & regulators relate

[Jad]

Thank you very much for the response, I am new in the power supply of MCUs and would like to know what could be the problems if I put 2 boards in serial. And if you have any tips regarding the power of MCUs in general, my main goal is to power up 3 MCU's and a light  with a 12 volt power supply

[SofLit]

What do you mean by that?

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@Jad wrote:

 I put 2 boards in serial. 

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I think it's better to plot a sketch with different blocks and different power supply levels at each stage and share it here to understand what do you need to do ..

[Jad]

Thank you for the response. I can't have a value before running my program on the board. Because for my project, what I wanted to do is to choose the sensors in a matter of the power supply that I get from the MCU, so I can power up all my sensors from my MCU.

[Jad]

allright, I will open a new case for that topic